This invention relates to a method for manufacturing stockings, socks and the like and closing the toe thereof, on knitting machines of the type with two needle cylinders.
As is well known, many tubular knitted socks or stockings, both for men and women, especially if made of cotton or analogous yarns and according to various designs, are generally manufactured on circular knitting machines with two cylinders comprising an upper and a lower needle cylinder, in which needles hooked at their two ends may work and slide from one cylinder to the other. From such machines, the stockings or socks, come out with the toe part still open which then requires successive closure operations by means of sewing or linking which notably increase the final manufacturing cost of the socks or stockings.
Furthermore in such machines, the socks or stockings are manufactured so as to follow one after the other with the interpositioning of a waste length of fabric which has to be eliminated by a successive operation with consequent further increase of the cost.
Methods and processes to carry out the closure of the toe parts of stockings or socks directly on circular knitting machines have been suggested as for inst. in U.S. Pat. No. 3,340,706. Such methods are applicable on circular knitting machines with only one needle cylinder.
More particularly, it is well known that knitting machines with one cylinder only include a dial, on which a plurality of hook elements may slide radially, a purpose of which is to hook and to hold yarns or loops of a course of the fabric, especially when reinforced zones have to be formed. It has been already suggested to use the said hooks of the dial for carrying out the toe closure on a single cylinder knitting machine. In this case, assuming that the toe portion of the stocking is made as the last part, a selection of the needles is effected in order to bring a group of needles, for instance alternate needles, in an inoperative position in the needle cylinder in which they limit themselves to the holding of a relative loop of fabric while the hook elements arranged in correspondence of the said needles above them are pushed to project from the dial and hold the yarn, starting from which the remaining needles, which continue to work, knit a new fabric portion. Thus an additional fabric is manufactured, which is held at one side thereof by the needles in inoperative position and at the other side by the hook elements, which additional fabric has the form of an annular pocket. The knitting of this pocket is continued until it has reached a sufficient length to be centrally bound by a further yarn which thus tightens the pocket in correspondence of the axis of the needle cylinder. The two peripheral courses of the pocket, which were held by the hook elements and the inoperative needles, respectively, are then interknitted, thus forming a double layered toe portion directly closed on the machine.
It has been furthermore proposed to transfer this working principle to double cylinder knitting machines, by suggesting that the role of the hook elements, as holding means for some loops, may be taken over by needles arranged in the upper needle cylinder.
A method has therefore been suggested according to which the stocking is manufactured from top portion to toe portion, the leg and foot portion being manufactured with the needles in the lower needle cylinder. The toe portion is manufactured by effecting a selection of the needles, raising a first group thereof to the upper needle cylinder where they assume an inoperative position and retain relative loops of the fabric already knitted, and leaving the remaining needles in the lower needle cylinder. The toe portion is then continued by knitting with the needles remained in the lower needle cylinder, thus forming a pocket similar to that already described above. After the pocket has reached the desired length there occurs a central binding of the pocket and then the needles brought to the upper needle cylinder are lowered to the lower needle cylinder and all the needles are made operative and interknit the final portion of the pocket and the initial portion thereof. The method further comprises the formation of a tab portion having anti-ravelling purposes, this tab being necessary when the stocking is commenced at the leg portion and terminated at the toe.
The said method, which directly derives from adapting the method known on single cylinder knitting machines to a double cylinder knitting machine, requires that the fabric, which is manufactured by the needles in the lower needle cylinder, is taken up through the upper needle cylinder otherwise it would not be possible to make the pocket and close it. Additional means have, therefore, to be arranged on the top of the upper needle cylinder for pulling the fabric. The said means increase the height of the double cylinder knitting machine and entail that a novel machine is designed for carrying out the method. It would appear that a reversion of the operative steps, that is knitting the leg and foot portions on the upper needle cylinder and take up the fabric through the lower needle cylinder, would avoid these drawbacks. Such an operation, however, would require additional operation to be carried out on the stocking since the stocking would require turning inside out when finished.